A change from 2.4.18 to 2.4.19 has broken the way that devfs maps
root=. 2.4.18 init/main.c::mount_root() has
devfs_make_root (root_device_name);
handle = devfs_find_handle (NULL, ROOT_DEVICE_NAME,
MAJOR (ROOT_DEV), MINOR (ROOT_DEV),
DEVFS_SPECIAL_BLK, 1);
where ROOT_DEVICE_NAME maps to the value of root= for non-initrd. This
allowed devfs to remap an entry such as sda3 to whatever driver was
implementing sda3, even if that driver used a different major number.
The correct major was returned in handle.
2.4.19 init/do_mounts.c::mount_root() has
devfs_make_root(root_device_name);
create_dev("/dev/root", ROOT_DEV, root_device_name);
create_dev() has
handle = devfs_find_handle(NULL, dev ? NULL : devfs_name,
MAJOR(dev), MINOR(dev), DEVFS_SPECIAL_BLK, 1);
The difference in 2.4.19 is that if dev is already set from
root_dev_names[] then devfs does NOT get the value of root=, forcing
the use of major from root_dev_names[]. If a driver reimplements one
of the standard device names and uses a different major or minor number
then it no longer works in 2.4.19 because devfs is given incomplete
information.
Quick and dirty workaround
--- 2.4.19/init/do_mounts.c
+++ 2.4.19/init/do_mounts.c
@@ -368,7 +368,7 @@
if (!do_devfs)
return sys_mknod(name, S_IFBLK|0600, kdev_t_to_nr(dev));
- handle = devfs_find_handle(NULL, dev ? NULL : devfs_name,
+ handle = devfs_find_handle(NULL, devfs_name,
MAJOR(dev), MINOR(dev), DEVFS_SPECIAL_BLK, 1);
if (!handle)
return -1;
But that probably breaks initrd. What should that code be doing to
cope with both initrd and still allow devfs to remap root=?